Colorado State University

About: Colorado State University is a education organization based out in Fort Collins, Colorado, United States. It is known for research contribution in the topics: Population & Laser. The organization has 31430 authors who have published 69040 publications receiving 2724463 citations. The organization is also known as: CSU & Colorado Agricultural College.

Navigating the Anthropocene: Improving Earth System Governance

Abstract: Science assessments indicate that human activities are moving several of Earth's sub-systems outside the range of natural variability typical for the previous 500,000 years ( 1 , 2 ). Human societies must now change course and steer away from critical tipping points in the Earth system that might lead to rapid and irreversible change ( 3 ). This requires fundamental reorientation and restructuring of national and international institutions toward more effective Earth system governance and planetary stewardship.

Hyphal uptake and transport of nitrogen from two 15n‐labelled sources by glomus mosseae, a vesicular‐arbuscular mycorrhizal fungus *

Abstract: SUMMARY Celery (Apium graveolens L.) plants were grown in pots in which the root system was separated from the soil in a side chamber by a fine mesh screen. The side chamber was treated with either an organic (ground plant tissue) or inorganic [(NH4)2SO4] source of 15N. Mycorrhizal (Glomus mosseae) and control (non-mycorrhizal) plants were exposed to 15N over a period of 30 days (inorganic-15N) or 88 days (organic-16N). Mycorrhizal and control plants did not differ in shoot dry weight or shoot P content. Dry weight of root was reduced in the mycorrhiza treatments. Mycorrhizal plants derived significantly (P= 0.01) more 16N, from both N sources, than did control plants. In the inorganic-N treatment, 15N in mycorrhizal plants was significantly (P= 0.001) and positively correlated with percent mycorrhizal fungal colonization (r= 0.58), number of hyphal crossings (±10 μ diameter) through the mesh into the area of 15N placement (r= 0.76), total length of hyphae per gram of soil (r= 0.74), and length of hyphae of 5 μ diameter in the soil (r= 0.77). No correlations were found between the 16N content of mycorrhizal plants and any parameter in the organic-N treatment. The 16N content of control plants was not correlated with hyphal length in the outer chamber and there were no hyphal crossings of the size ( 10 μ diameter) which was counted for the mycorrhiza treatments. The presence of the organic matter (ground plant tissue) increased the total length of saprophytic hyphae per gram of soil but decreased the number of vesicular-arbuscular mycorrhizal fungal hyphae crossing into the area of 16N placement. The mean flux of N through the hyphae of G. mosseae was 7.42 × 10−8 mol N cm−2 s−1 for the inorganic-N treatment over a 30-day period, and 1.74 × 10−8 mol N cm−2 s−1 for the organic-N treatment over an 88-day period.

Levoglucosan stability in biomass burning particles exposed to hydroxyl radicals

Abstract: [1] Experiments were carried out in a smog chamber to investigate the oxidation of levoglucosan in biomass burning particles exposed to gas-phase hydroxyl radicals (OH). The experiments featured atmospherically-relevant particle and oxidant concentrations and both high and low relative humidity conditions. In every experiment, we observed levoglucosan decay in particles exposed to OH. The extent of decay ranged from ∼20% to ∼90% and was strongly correlated to the integrated OH exposure. Increased relative humidity did not enhance or impede reaction. Relative kinetics indicate that levoglucosan has an atmospheric lifetime of 0.7–2.2 days when biomass burning particles are exposed to 1 × 106 molecules cm−3 of OH (typical average summertime conditions). This implies that levoglucosan reacts with OH on a timescale similar to that of transport and deposition, which has important implications for the use of levoglucosan as a tracer for biomass burning emissions in source apportionment studies.